This proposal is part of the Collaborative Studies of the Psychobiology of the Depressive Illnesses, which are under the aegis of the Clinical Research Branch of the Division of Extramural Research Program of the NIMH. The purpose of the Collaborative Studies is to clarify the nosology of the depressive illnesses, examine the role of genetic factors in the development of depression, and explore the relationship between clinical, biological and psychophysiological variables. The present proposal is to continue work on the main clinical assessment procedures for these studies: the Schedule for Affective Disorders and Schizophrenia (SADS), and the Research Diagnostic Criteria (RDC). The SADS utilizes a structured interview to obtain the information from the patient, contains both a current and a past section, comprehensively evaluates a broad range of symptomatology and functioning, and can be used for purposes of classification as well as measurement of change. The proposedwork includes two parts: the first is primarily methodological and includes further work on the schedule for Affective Disorders and Schizophrenia, the development of training materials and and algorithms for assigning patients by several classification systems and determining the reliability of the items and the classificatory algorithms. The second is more substantive and is dependent upon the availability of data collected from the Pilot Collaborative Study. This work includes examining the distribution of patients in the various classification systems, and analyzing the data in terms of the hypotheses of the larger study and the relationship between assessment instruments.